The present invention generally relates to seat belt retractors and inertial sensors used therein.
A typical seat belt retractor is designed to be installed within a vehicle at a fixed position such as on the B-pillar or attached to a non-rotatable portion of the seat frame. In this type of application, the vehicle sensor, that is, the inertial sensor which responds to changes in vehicle deceleration (acceleration or rollover events), is supported relative to the retractor frame such that its corresponding inertial mass is at a nominal, typically vertical position (aligned to the local gravity vector). The conventional vehicle sensor includes a housing having a support surface, a weight (such as a standing man, pendulum, ball or weighted member with a lower spherical surface) and an actuator lever. The weight moves upon the support surface and as it does, changes its elevation thus engaging the actuator lever, and pushing the lever into engagement with another retractor part, typically the teeth of a ratchet wheel. The housing is usually permanently attached to a frame of the retractor. The lever is pivoted at one end, the pivot end, by the sensor housing. This simple type of construction cannot be applied to a retractor that is mounted within the seat back of the automotive seat unless provision is made to maintain the verticality of the support structure, such as the sensor housing, and the inertial mass as a function of the angle of the seat back. As can be appreciated, in the conventional vehicle sensor which is secured to the retractor frame, if the retractor is tipped, for example as the seat belt is moved, the vehicle sensor will be moved to a non-working or performance reducing orientation.
Reference is briefly made to FIGS. 1a and 1b which illustrate a prior art three-point, seat-integrated-belt (SIB) safety restraint system.
The three-point SIB system 20 of FIG. 1a includes a retractor 22 secured to the vehicle seat generally shown as 24. More particularly, the retractor 22 is secured to the frame 26. This frame or frame part 26 is located within the seat back 28. The seat 24 may also include an exit opening 30 through which the shoulder belt 32 of a seat belt 34 exits. The other end of the shoulder belt is wound about a spool (not shown) of the retractor 22 in a conventional manner. The seat belt 34 is separated into the shoulder belt portion 32 and a lap belt portion 36 at the juncture of a tongue 38 also in a known manner. The opposing end 40 of the lap belt is secured via an anchor 42 (or a lap retractor) to a frame portion such as 44 of the seat 24 or to the vehicle floor 46. The tongue 38 is insertable within a buckle 47 which is appropriately secured at via anchor 48 to the seat 24 or to the floor 46. The seat 24 additionally includes a seat cushion 50. The seat back 24 is typically movable through a range of positions, from a nominal position designated as 24a (in FIG. 1b) to a reclined position 24b or to a forward position 24c. It should be appreciated that the positions 24b and 24c are merely illustrative and that the angular movement of the seat back may be larger or smaller than the extremes shown. In certain situations it may be desirable to ensure that the seat belt retractor is in a pre-lock condition such as when the seat back is in a near-vertical orientation, about 3.5.degree. (forward rotation) to -8.5.degree. (rearward rotation), such as illustrated in position 24c, or when the seat back has been reclined, such as in position 24b, to an orientation that is between 25.degree. and 45.degree. or more. By pre-locked it is meant that the various elements of the retractor sensing system have been moved into an orientation such that if the seat belt is then protracted from the retractor, the retractor will be placed into a locked condition, as the seat belt is protracted, regardless of the speed of seat belt protraction or level of vehicle deceleration.
In an SIB environment the retractor 22 will be placed much closer to the occupant's head 52 than if the retractor were located behind trim at the base of the B or C pillars of the vehicle. This positioning has been exaggerated in FIG. 1b. As such, any contact or vibrationally induced sounds (typically referred to as buzz, rattle and squeak in the automobile industry) need to be minimized, as there might not be sufficient attenuation by the seat structure, trim or foam cushion. Depending on actual road conditions, the vehicle may be subjected to inertial inputs in excess of 0.7 g which emphasizes the need for noise attenuation in all vehicle components.
It is an object of the present invention to provide a seat belt retractor that is characterized by quiet operation. A further object of the present invention is to provide the seat belt retractor that is operable in a plurality of rotated seat back orientations. A further object of the present invention is to provide a seat belt retractor that is mounted within a seat back, and which is placed in a pre-locked condition when the seat back is oriented in one or more lock zones defined by extremes of seat back rotation.
Accordingly the invention comprises a seat belt retractor having a noise reducing self-compensating inertial sensor. The sensor is usable in a variety of sensor housing configurations or assemblies (such as fixed or self-compensating). One of these sensor housing assemblies includes a cantilevered support pin with a rotational actuator lever mounted thereupon. The pin and actuator lever configuration can be used in a simple fixed sensor housing or in more complicated self-compensating sensor assemblies as illustrated below in which a plurality of pins and levers are employed. A variety of inertial weights (or sensor masses) may be used with the improved multi-pin and multi-lever configuration of the present invention. The inertial sensor includes a weight having a metallic body insert molded with an elastomeric material to reduce contact noise with a cooperating sensor lever contacting the top of an elastomer-filled portion of the sensor mass (weight). The sensor further includes an elastomer layer at its base to reduce noise between the sensor mass and a support surface (provided by the sensor housing).
Many other objects and purposes of the invention will be clear from the following detailed description of the drawings.